The present invention relates in general to pollution control devices in internal combustion engines. In particular, the present invention is directed to a positive crankcase ventilation (PCV) system of an internal combustion engine.
Generally, internal combustion engines acquire power by igniting an air-fuel mixture in a combustion chamber, and during the combustion process a lot of emission gases are generated. The emissions gases are then cleaned and emitted through an exhaust system.
Combustion gases produced in the combustion chamber of an internal combustion engine are commonly forced under pressure to flow past the piston rings of the engine and into the engine crankcase. Such gases are called xe2x80x9cblow-byxe2x80x9d gas, which usually consist at least partially of an air/oil mist. If the blow-by gas is emitted from the engine into the atmosphere, it causes air pollution. In order to satisfy emission regulations, such blow-by gas must be treated. Therefore, PCV systems have been developed for re-burning the blow-by gas.
Typical PCV systems include a PCV hose that connects the cylinder head rocker cover to the intake manifold. Thus, blow-by gas present in a chamber defined between the rocker cover and the cylinder head is drawn into the intake manifold through the PCV hose. The blow-by gas is thus mixed with air in the intake manifold, and the mixed gas flows back into the cylinder to be re-burned.
However, in conventional blow-by gas re-circulating systems, when the engine is rotating, the blow-by gas resides in air intake passageways such as the intake manifold, throttle body, air intake hose, air cleaner, and air duct leading to the outside of the system. Consequently, fuel particles and oil particles in the blow-by gas are accumulated in the air intake passageways. This may cause air pollution, and also degrades engine performance.
In a preferred embodiment of the present invention, a system for treating blow-by gas in a PCV system of an internal combustion engine comprises a cut-off valve assembly, a blow-by gas collecting assembly, and a controller. The cut-off valve assembly selectively opens or closes an air duct. The blow-by gas collecting assembly collects the blow-by gas inside an air intake passageway and ejects it into an intake manifold such that it is re-burned in a combustion chamber. The controller controls operation of the cut-off valve assembly and the blow-by gas collecting assembly.
Preferably, the cut-off valve assembly comprises a valve plate and an actuator. The valve plate is rotatably disposed in the air duct, and the actuator rotates the valve plate such that a position of the valve plate is changed, the actuator being controlled by a signal input from the controller. It is further preferable that the actuator is a step motor.
It is preferable that the blow-by gas collecting assembly comprises a pump, a gas reservoir, a first duty-control valve, a second duty-control valve, and a third duty-control valve. The pump is controlled by the controller and it draws the blow-by gas. The pump is connected to the air duct between the cut-off valve and an air cleaner through a first collecting hose and to an air intake hose between the air cleaner and a throttle body through a second collecting hose. The gas reservoir temporarily stores the collected blow-by gas; it is connected to the pump through a connecting hose and to the air intake hose through an ejecting hose. The first, second, and third duty-control valves are respectively disposed in the first and second collecting hoses and the connecting hose, each duty-control valve being controlled by signals input from the controller.
In another preferred embodiment of the present invention, the system further comprises a first pressure sensor and a second pressure sensor. The first and second pressure sensors respectively detect pressures inside the air duct and the air intake hose, and generate corresponding signals. The controller receives the signals of the first and second pressure sensors and controls the first, second, and third duty-control valves on the basis of the signals.
In an alternative preferred embodiment of the present invention, the system further comprises a breather hose and a PCV hose. The breather hose communicates an air intake hose and a rocker cover, and the PCV hose communicates a chamber under the rocker cover and an intake manifold, a PCV valve being disposed in the PCV hose.
Preferably, the controller generates a signal to close the air duct, and sends the signal to the cut-off valve assembly. It is also preferable that the controller generates signals for operating the pump and signals for opening the first and second duty-control valves, if an ignition-on signal is detected. The controller also may determine whether conditions for opening the air duct exist, the conditions including that a pressure inside the air duct is lower than atmospheric pressure and higher than a pressure inside the air intake hose using the signals input from the first and second pressure sensors. Signals for opening the air duct to the cut-off valve assembly, if the conditions for opening the air duct exist, are generated by the controller.
The controller preferably determines whether an engine speed is higher than 0 rpm and generates signals for opening the third duty-control valve if the engine speed is higher than 0 rpm.
Signals are also generated for stopping the pump and releasing duty-controls on the first and second duty-control valves. Whether the engine speed is equal to 0 rpm may be determined by the controller and then signals for closing the air duct to the cut-off valve assembly are generated if an engine speed is equal to 0 rpm.
In another preferred embodiment of the present invention, the system for treating blow-by gas in a PCV (positive crankcase ventilation) system of an internal combustion engine comprises an air duct opening/closing assembly, a pump, a gas reservoir, a first duty-control valve, a second duty-control valve, a third duty-control valve, a first pressure sensor, a second pressure sensor, and a controller. The air duct opening/closing assembly is disposed in an air duct before an air cleaner, the air duct opening/closing member selectively opening/closing the air duct. The pump collects blow-by gas from the air duct and an air intake hose, the pump being respectively connected to the air duct and the air intake hose through a first collecting hose and a second collecting hose. The gas reservoir temporarily stores the collected gas, the gas reservoir being connected to the pump through a connecting hose and also being connected to the air intake hose through an ejecting hose. The first duty-control valve is disposed in the first collecting hose, the second duty-control valve is disposed in the second collecting hose, and the third duty-control valve is disposed in the ejecting hose. The first pressure sensor detects a pressure inside the air duct and generates a corresponding signal, and the second pressure sensor detects a pressure inside the air intake hose and generates a corresponding signal. The controller controls operation of the pump and performs duty-control of the first, second, and third duty-control valves on the basis of the signals input from the first and second pressure sensors as well as engine operating conditions.
In another preferred embodiment of the present invention, the method for treating blow-by gas employs a PCV (positive crankcase ventilation) system of an internal combustion engine. The system preferably includes an air duct opening/closing assembly disposed in an air duct before an air cleaner. The air duct opening/closing member selectively opens/closes the air duct. A pump collects blow-by gas from the air duct and air intake hose. The pump is preferably respectively connected to the air duct and the air intake hose through a first collecting hose and a second collecting hose. A gas reservoir temporarily stories collected gas, the gas reservoir being connected to the pump through a connecting hose and also being connected to the air intake hose through an ejecting hose. A first duty-control valve is disposed in the first collecting hose. A second duty-control valve is disposed in the second collecting hose. And a third duty-control valve is disposed in the ejecting hose. A first pressure sensor detects pressure inside the air duct and generates a corresponding signal. A second pressure sensor detects pressure inside the air intake hose and generating a corresponding signal. A controller controls operation of the pump and performs a duty-control for the first, second and third duty-control valves on the basis of the signals input from the first and second pressure sensors and engine operating conditions.
Preferably, the method comprises operating the pump and opening the first and second duty-control valves, if an ignition-on signal is detected; determining whether conditions for opening the air duct exist, the conditions including that a pressure inside the air duct is lower than atmospheric pressure and higher than a pressure inside the air intake hose, using the signals input from the first and second pressure sensors; opening the air duct by controlling the cut-off valve assembly if the conditions for opening the air duct exist; determining if an engine speed is higher than 0 rpm; opening the third duty-control valve if the engine speed is higher than 0 rpm; and stopping the pump and releasing duty-controls on the first and second duty-control valves. More preferably, the method further comprises determining if an engine speed is equal to 0 rpm; and generating signals for closing the air duct to the cut-off valve assembly if the engine speed is equal to 0 rpm.